Fabric, especially clothing, can become soiled with a variety of foreign substances ranging from hydrophobic stains (grease, oil) to hydrophilic stains (clay). The level of cleaning necessary to remove foreign substances depends to a large degree upon the amount of stain which is present and to the degree and manner in which the foreign substance has contacted the fabric fibers. Grass stains usually involve direct abrasive contact with vegetative matter thereby producing highly penetrating stains. Human body oils and perspiration are continually produced and deposited onto fabric while clothing is being worn, especially at the collar, cuffs, and underarm areas. Body oils become embedded into the fabric not only by absorption or by wicking of the materials themselves into the fiber, but also by the mechanical action of the body against the fabric.
In many cases a surfactant per se is not all that is necessary to remove unwanted hydrophobic soils and stains. In the case of human body oils and other hydrophobic stains on collars, cuffs and other contact areas, perspiration and body oil stains are not fully removed by washing alone. Even hand scrubbing of collars does not ameliorate the dingy appearance of white cotton-comprising fabric. For hydrophobic soils, dispersants are ineffective because they act on soils which are removed and not on those which are embedded throughout the fabric surface fibers. Formulators have used soil release polymers to attenuate the spreading ut and absorption f greasy, ily material onto synthetic fabric, however, cellulosic fiber still presents the laundry formulator with the problem of dingy appearance due to human body oils and perspiration stains.
There is a long felt need in the art for laundry detergent compositions which can effectively solublize greasy, oily materials from the surface fibers of fabric, and once solublized, said oily materials can then be eliminated by the action of surfactants. There is also a long felt need for a cleaning system which effectively removes lipid type stains which have been worn into fabric by mechanical action of skin against fabric, for example, at shirt collars and cuffs.